Category Archives: Linux

Install low latency kernel on Ubuntu (Studio) 10.10 (Maverick)

After upgrading my Ubuntu from 10.04 to 10.10 I’ve noticed that there was no realtime or low latency kernel for it�Cry

The standard kernel behaves very well (for a standard kernel at least) with audio applications, at least up to what I tested – hydrogen, rackarrack (even with heavy processing effects) and 2 instances of ZynAddSubFx. �But I want to test Maverick with audio applications at least with a Low Latency kernel, so I used google, and found some references for how to do it.�Unfortunately�they link to unavailable kernel versions. I’ve also asked in Ubuntu Studio mailing list and�Mike Holstein said that he used the process described in the following link:

http://jackschnippes.freeunix.net/index.php/2010/11/04/lowlatency-kernel-and-realtime-kernel-for-ubuntu-10-10-maverick

This was one of the links I have found googling, and has the problem of broken link (the kernels referenced are not available anymore). So to make the story short, I’ve searched for newer kernel packages and headers (these are for Natty (11.04) but work on Maverick), and this is what I have done to have a low latency kernel installed in my Ubuntu Maverick (10.10) home studio PC (AMD64):

First, download the packages (headers from a Ubuntu Natty mirror, kernels from Alessio PPA):�

wget�http://mirror.pnl.gov/ubuntu//pool/main/l/linux/linux-headers-2.6.37-12_2.6.37-12.26_all.deb

wget�http://ppa.launchpad.net/abogani/ppa/ubuntu/pool/main/l/linux-lowlatency/linux-headers-2.6.37-12-lowlatency_2.6.37-12.26~ppa3_amd64.deb

wget�http://ppa.launchpad.net/abogani/ppa/ubuntu/pool/main/l/linux-lowlatency/linux-image-2.6.37-12-lowlatency_2.6.37-12.26~ppa3_amd64.deb

Then, install the packages:

sudo dpkg -i�linux-headers-2.6.37-12_2.6.37-12.26_all.deb

sudo dpkg -i�linux-headers-2.6.37-12-lowlatency_2.6.37-12.26~ppa3_amd64.deb

sudo dpkg -i�linux-image-2.6.37-12-lowlatency_2.6.37-12.26~ppa3_amd64.deb

And Voil�, a working low latency kernel on Maverick�Tongue out

For i386 architectures (didn’t test it), you can use the following packages instead:

PAE (more than 4GB RAM):

http://ppa.launchpad.net/abogani/ppa/ubuntu/pool/main/l/linux-lowlatency/linux-headers-2.6.37-12-lowlatency-pae_2.6.37-12.26~ppa3_i386.deb

http://ppa.launchpad.net/abogani/ppa/ubuntu/pool/main/l/linux-lowlatency/linux-image-2.6.37-12-lowlatency-pae_2.6.37-12.26~ppa3_i386.deb

Non PAE:

http://ppa.launchpad.net/abogani/ppa/ubuntu/pool/main/l/linux-lowlatency/linux-headers-2.6.37-12-lowlatency_2.6.37-12.26~ppa3_i386.deb

http://ppa.launchpad.net/abogani/ppa/ubuntu/pool/main/l/linux-lowlatency/linux-image-2.6.37-12-lowlatency_2.6.37-12.26~ppa3_i386.deb�

Now it is time to test this new kernel, but this will be another article. Please post any comment or correction, as I said I didn’t test the i386 platform, so you could post your results. I want to thank to Mike for its help in the Ubuntu Studio mailing list (and all the other users from Ubuntu Studio mailinglist that gave me suggestions about this) and Alessio for its�excellent�work with the low latency and realtime kernels.
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How to flash the BIOS without a floppy, using the CD-ROM

This is based on this how-to from Ubuntu forum, I’ve tested the CD-ROM method and it works flawlessly :-)

In summary, after being sure that a bios update is REALLY necessary, this is what I’ve done:

wget http://www.fdos.org/bootdisks/autogen/FDOEM.144.gz
gunzip FDOEM.144.gz
mkdir /tmp/cdr
sudo mount -t vfat -o loop FDOEM.144 /tmp/cdr
sudo cp ~/NewBiosFiles/* /tmp/cdr
sudo umount /tmp/cdr
sudo apt-get install mkisofs
mkisofs -o newBIOS.iso -b FDOEM.144 FDOEM.144
cdrecord -v newBIOS.iso

I hope this can be useful if you need to upgrade the BIOS and don’t have a floppy (and in my case the BIOS also didn’t support USB boot using a PEN, in that case I could use unetbootin to make a bootable DOS pen like I normally do with other PCs.

 

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Openmeetings VMWare appliance

I’ve made a VMWare image running Openmeetings, V1.0 RC1, available here

The operating system is Ubuntu 9.04 Server Edition, username administrator, password is password. The same username and password was used for the Openmeetings login. MySQL root password is password. All functions are configured, including OpenOffice server for document conversion.

When starting the VM, VMWare will ask if the VM was moved or copied. I suggest to choose ‘moved’, if you choose ‘copied’, VMWare will create a new MAC Address for the network interface and the VM will start with no network interface (it has to be manually reconfigured to match the new MAC Address)

The VM is using DHCP (you will have to execute ifconfig to know its IP address and have a DHCP server running in your network). If you need to configure a fixed IP address you have to manually reconfigure the network interface.

I’m using the VM with version 0.9RC5 for videoconference inside my company and it is working well. The VM with version 1.0RC1 has been less tested, but all the tests made succeeded, so I think you should prefer the V1.0 RC1. If you find something not working feel free to post a comment (you have to register, because do to all the spam I have restricted anonymous comments on this site)�

 

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Ubuntustudio 9.10 (Karmic) beta

I’ve installed the Ubuntustudio 9.10 daily release today and it worked almost without a problem. It is working on my homestudio PC (AMD 780G chipset with a Athlon 64 X2 processor) where the previous Ubuntustudio 9.04 and 8.10 failed to boot and I had to use Ubuntustudio 8.04 or a custom built rt kernel for the 9.04 release. Now for the (few) problems:

  • Grub installation asked for including a menu item for the Windows installation already present on my PC, but it didn’t include the menuitem, so I had to include it manually
  • It detected the availability of restricted hardware drivers (ATI), but failed to install it
  • When using audio in realtime the system hangup from time to time, blocking eerything (keyboard, mouse), but leaving the ‘RT’ label on jack client flashing slowly.

So these are the first impressions, not bad for a beta release, extremely fast boot and shutdown time (it seems about half the time I had with 8.04, but didn’t measure it), and my homestudio PC hardware seems now do be (almost) supported :-) Continue reading

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Howto install Rackarrack on Ubuntu / Ubuntustudio 9.10 (Karmic)

Rackarrack is an excelent realtime guitar effect processor for Linux, unfortunately not yet included on Ubuntustudio.� I’ve followed this tutorial to install it on Ubuntustudio 9.10 beta (Karmic), and it worked very well, so I’m including here the steps necessary to do it (I suppose it would also work on previous Ubuntu versions):

Add all the necessary dependencies:

sudo aptitude install jackd libjack-dev libjack0.100.0-0 libjack0.100.0-dev libfltk1.1 libfltk1.1-dev libasound2-dev libxpm-dev aconnectgui

Add the necessary developer tools (compiler, make, etc):

sudo aptitude install build-essential

Get the Rackarrack source here, extract it, change to its directory and execute:

./configure

make

sudo make install

The original tutorial has a link to a .deb package for the amd64 architecture, I haven’t tested it.

Good luck!

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Limiting CD / DVD drive noise

I have an home theater PC based on a NVidia ION motherboard (ZOTAC), and I had a strong noise produced by the DVD drive, because it runs at full speed when it has a disk inside. Using the following command the drive speed is limited to x2, making an acceptable noise for its function.

hdparm -E 2

If you already have the CD/DVD disk in the drive you have to remove it and insert it again in order to enable the drive speed change

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Howto make a linux RT Kernel (2.6.31-rc7)

Get the kernel sources and corresponding rt patch (the versions might be different, this was done at the end of August 2008, when the latest rt patch available was for the kernel 2.6.31-rc7, the important thing to consider is to use a patch matching with the kernel source):

sudo apt-get install build-essential
sudo -s
cd /usr/src
wget http://www.kernel.org/pub/linux/kernel/v2.6/testing/linux-2.6.31-rc7.tar.bz2
wget http://www.kernel.org/pub/linux/kernel/projects/rt/patch-2.6.31-rc7-rt8.bz2
chmod 755 *
tar xjfv linux-2.6.31-rc7.tar.bz2
rm linux
ln -s linux-2.6.31-rc7 linux
cd linux
bzip2 -dc /usr/src/patch-2.6.31-rc7-rt8.bz2 | patch -p1 --dry-run
bzip2 -dc /usr/src/patch-2.6.31-rc7-rt8.bz2 | patch -p1
cp /boot/config-`uname -r` .config
make menuconfig

Change the following parameters:

Processor type and features --->
Preemption Mode (Complete Preemption (Real-Time)) --->
( ) No Forced Preemption (Server)
( ) Voluntary Kernel Preemption (Desktop)
( ) Preemptible Kernel (Low-Latency Desktop)
(X) Complete Preemption (Real-Time)
Processor type and features  --->
Timer frequency (1000 HZ) --->
(X) 1000 HZ
Drivers
 ( ) Staging drivers 

Now build the kernel and install it:

make-kpkg clean
make-kpkg modules_clean
make-kpkg --revision 1 --initrd kernel_image kernel_headers modules_image
cd ..
chmod 755 *
dpkg -i *31-rc7*.deb

To avoid the following error during / after kernel installation:

/etc/kernel/postinst.d/nvidia-common exited with return code 20

I had to execute this command:

sudo apt-get remove –purge nvidia-common

This worked for me because I have no NVidia components on my system (graphic card or chipset).

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Burn Audio CD from MP3 files (using k3b)

On 64Studio 3.0 Beta 3 (ubuntu based) I needed to burn an audio cd from MP3 files. First I have installed my favorite burning software, k3b:

sudo apt-get install k3b

Then I found that is not capable of recording directly audio from mp3 files, so I have installed also the libk3b2-extracodecs:

sudo apt-get install libk3b2-extracodecs

And it worked!

Great program k3b!

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Howto recover grub after windows installation

To recover grub:

Boot with a live CD (in my case I use Ubuntu 8.10 live CD)

sudo grub

root(hd0,0)

setup(hd0)

quit

To put windows boot option on grub:

Run fdisk -l to see the partition where windows is installed (normally NTFS or FAT32). In my case the result was that the NTFS partition was the thirs (sda3 NTFS). Now we have to edit the grub boot options and configure it accordingly (third partition will be number 2, because for grub the index starts on zero)

Edit …. and put the following lines at the end of file:

title Windows

root(hd0, 2)

makeactive

chainloader +1

�The parameter hd0 means that it is on the first disk (in my case I only have a single sata disc on this PC)

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